The present invention relates to a silicone foam composition and more particularly the present invention relates to SiH-olefin platinum catalyzed silicone foam composition in which the novel foaming ingredient is water.
Accordingly, in the construction of many plants and buildings there are many steps taken to insulate electrical systems and more specifically sensitive electrical systems, such that in the case of fire that they will not burn easily and that if they do burn they will not propagate a fire very easily.
Accordingly, silicones with their high temperature properties are highly desirable as insulative materials for such electrical systems. For instance, silicones may tend to char and leave a protective ash on the system that they are insulating and still protect the electrical system and maintain its electrical integrity. Accordingly, such burn resistant properties of silicones have made them highly desirable as insulative materials for electrical systems and more specifically for cables. Thus, one use of heat vulcanizable silicone rubber compositions comprising a diorganopolysiloxane gum, silica filler, flame retardant additives such as platinum or carbon black and with or without a peroxide catalyst has been to fill the voids in electrical cables thus protecting the cable in case of fire.
Accordingly, in such uses it has been found that such heat vulcanizable silicone rubber compositions either in the cured or in the uncured state with a base composition disclosed above alone or with the addition of other flame retardant additives have protected the electrical integrity of the cables up to temperatures of 2000.degree. F. for an appreciable period of time.
Accordingly, it was highly desirable to utilize such burn resistant silicone compositions as insulative materials for electrical systems and specifically electrical systems in nuclear plants. Concrete can be used to enclose and protect such elecrical systems. However, the cost of applying the concrete to irregular openings in walls and ceilings becomes quite expensive.
Accordingly, it became desirable to utilize for the insulative protection of such electrical systems silicone foams. As a matter of fact, flame retardant silicone foams are highly desirable not only for the enclosure and protection of electrical systems but also for the protection of other types of components from burning to some extent.
An example of such a flame retardant silicone foam is that, for instance, to be found in Modic, U.S. Pat. No. 3,425,967. This patent discloses a silicone foam composition which is produced by mixing and interracting a vinyl chain-stopped polysiloxane, an organopolysiloxane copolymer which was a resin composed of mono-functional units and tetrafunctional units and optionally difunctional siloxy units and inorganic fibrous material selected from the class consisting of asbestos and fibrous potassium titanate, optionally a finely divided inorganic filler, a platinum catalyst and an organo hydrogen polysiloxane and finally a blowing agent.
The examples that are given of such blowing agents are, for example, azo-isobutyronitrile, dinitrospentemethylene tetramine, benzenesulfonhydrazide N,N'-dinitroso-N,N'-dimethylterephthalamide, p,p'-oxy-bis(benzenesulfonhydrazide), terephthalazide, azodicarbonamide, etc. Such a system while adequate for many aspects had two main disadvantages. It required the use of a complex blowing agent which increased the cost of the system and also was foamed at elevated temperatures; that is, in order to activate the blowing agent elevated temperatures were needed and accordingly a foam could not be formed in situ in an electrical system already in place at room temperature since external heating had to be applied.
A more recent attempt to produce an acceptable silicone foam for the insulation of electrical systems from fire is to be found in the disclosure of Smith, U.S. Pat. No. 3,923,705. This patent reviews some of the prior art with respect to silicone foams. The disadvantages with such a system was that it required the reaction of a silanol containing polysiloxane with hydrogen-containing polysiloxane. There was found that with such a system good foams were not always produced unless an extremely active platinum complex catalyst was utilized. The reason for this is that if an extremely active platinum complex catalyst was not utilized then the hydrogen polysiloxane reacted with hydroxy-containing polysiloxane at a slow rate, releasing hydrogen at a slow rate and as a result a foam with a proper density was not always obtained. Accordingly, the type of foam and the amount of foam would vary from reaction to reaction and from batch to batch of the composition.
Accordingly, it was highly desirable to find a silicone foam which was not expensive and which would produce a reproducable foam from batch to batch that could be produced with most types of platinum catalysts.
In addition, in the construction of many buildings and partitions in buildings where concrete or masonry products were not utilized to produce the partition, it has been common to leave such partitions hollow or not containing any material in them.
Accordingly, it has been common especially in office buildings to leave such ceilings and more particularly partitions hollow. It was early suggested that silicone compositions could be utilized both as heat insulative materials and more particularly and more importantly as burn resistant materials in such partitions and ceilings.
Accordingly, it is highly desirable to have a silicone foam which is inexpensive and can be foamed at room temperature to a good quality foam from batch to batch with most types of platinum catalysts. Such silicone foam can also be used as a burn resistant material in partitions in the construction of partitions in buildings and as an insulative material in the ceilings of buildings.
Accordingly, it is one object of the present invention to provide for an SiH-olefin platinum catalyzed silicone foam.
It is another object of the present invention to provide for an SiH-olefin platinum catalyzed silicone foam which can be catalyzed with most types of platinum catalysts to produce good quality foam which is reproducable from batch to batch.
It is yet an additional object of the present invention to provide for a process for producing an SiH-olefin platinum catalyzed silicon foam of good quality which is resistant to burning.
It is yet an additional object of the present invention to provide for a process for insulating electrical systems by utilizing an SiH-olefin platinum catalyzed silicone foam composition. These and other objects of the present invention are accomplished by means of the disclosure set forth hereinbelow.